[extropy-chat] "Dead Time" of the Brain

[Robert Bradbury]

I'd suggest that the people reading this thread go do some googling or some
wiki-ing on precisely how neurons function.  In particular you have several
possibilities for time slicing.  Slices during which no atom in the brain
effectively moves (neurons electrical transmission depends on the flow of
sodium and potassium ions into and out of neurons -- no ion flow = no
electrical transmission).  Then there is the synapse transmission process
which involves (a) the movement of neurotransmitter vesicles from within an
axon terminal to fuse with the cell membrane and release the
neurotransmitter, (b) the diffusion time of the neurotransmitters across the
synapse and (c) the accumulation of neurotransmitters in sufficient quantity
to trigger the electrical transmission process in the receiving neuron.

You can calculate the time it takes ions to diffuse across a cell membrane
or the neurontransmitters to diffuse across the synaptic gap based on the
mass of the ions or molecules and the temperature [1].  See Nanomedicine
Vol. I Section 3.2 (it should be online).

But a better way of dealing with this discussion is to simply agree with
Heartland.  Yes, OK, so when I'm frozen or vitrified my synapses don't
release and take up molecules and my axons don't transmit electrical
signals.  I'm DEAD!  So *what*?  If a majority of what remains of my
functioning brain is restored to a functional condition (or if the
information it contains is supplied to a brain simulator) I have "risen"
from the dead.  Since I'm I a reasonable person I can be perfectly happy
acknowledging that I was dead and have subsequently been resurrected.

Since my resurrected self presumably will be happy to acknowledge, just as
my pre-death self is now, that -- Yes indeed, I was really and truly 'dead'
-- I challenge Heartland to propose an argument, other than a semantic one
of the form "once all your brain activity stops you are dead", that would
convince me that I should really *care* about this.  Hell, I don't care that
much if the solar system gets particularly crowded and I have to be
suspended 9 out of every 10 years or 99 out of 100 years to allow for a
couple of orders of magnitude more "minds" to have their share of the
resources available (I presume that there may be groups or generations of
"friends" who may choose to be suspended on synchronized schedules).

Robert

1. Don't hold me to any of this -- its been 15+ years since I took
physiology.
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